Currently notifications page seems a bit cluttered with no clear
separation between e-mail and filtering settings. This commit tries to
address them by adding clear separation with headers, hints and removing
continuously reused texts for events checkboxes.
Trending counter used to be constant 100px in width, which caused
issues in languages like Russian, where because of that, "talking"
text was cut to the size where actual count is not visible at all:
> 6 people talking
> Популярно у...
Sasha Sorokin